Football pros may be raking in millions while they are stars on the field, but it's well-known that many of them run into financial trouble after retiring. Now, a former defensive lineman wants to help those players invest their money and save for the future.

Leonard Marshall, who played with the New York Giants, New York Jets and Washington Redskins, is a partner with the Playbook Franchise Fund, which invests in franchise businesses.

Many players' biggest issue is their "ability to transition from the game" and "acclimate themselves in real life," Marshall said in an interview with CNBC's "Closing Bell" Thursday.

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New York Giants’ Leonard Marshall (70) is shown during an NFL football game against the Tampa Bay Buccaneers in Tampa Bay, Fla., Nov. 24, 1991.

Bad habits can start early and the fund's goal is to help players develop better spending and saving habits, saidSteve Levenson, founder of Playbook Franchise Fund.

In 2009, Sports Illustrated estimated that 78 percent of players face bankruptcy or severe financial stress two years after leaving the NFL. The NFL has disputed that figure, but it is trying to help its players prepare for life off the field. Earlier this year it held its first NFL Consumer Products Boot Camp, where players learned skills they hoped would help them once they leave the game.

"Too many of the young players that are making a lot of money don't have the life experience to know that it's not a repeatable pattern and they're attracted to what I call shiny objects: nightclubs, bars, restaurants, record labels, things like that," Levenson told "Closing Bell."

He said the fund gives investors access to ownership in a "very stable" franchise industry, with the fund taking on the operation and management of the businesses.